Wire for Steppers

[ger21]

I'm was looking on EBAY for some wire for my steppers. I see some 4 conductor wire for alarms labeled power limited circuit wire. What exactly does this mean, and is it good wire for steppers. Thanks.

Gerry

[ToyMaker]

Gerry:
Alarm wire is probably not suitable for power. It is typically quite fine. Look at the wires on your motors and try to find something that is comparable. The leads on my steppers are about 18 AWG stranded.
As an aside, you should try to keep the length of wire between the power supply and the motor as short as possible.

robotic regards,

Tom

[ger21]

My steppers connectors take 22 awg. As long as the alarm wire is 22 awg as well, it shouldn't make a difference, should it? I was just wondering what "power limited" meant. Does this mean the wire can't handle high current? Would it be adequate for 2.5a and 24V?

Gerry

[balsaman]

It would probably be ok. I have seen fellows use that ribbon cable that you find in computers for the drives etc. It's really small. A little bigger would be better. The smaller the wire the more voltage drops across it, as it has higher resistance. Another thing to consider is it's flexibility. You want it to be stranded wire, not solid.

Eric

[ger21]

22 awg is what the motor manufacturer calls for. It is stranded. 4 individualy insulated wires in a single outer insulation. I can't connect a larger wire than the 22awg to the motor connectors, I already tried.

Gerry

[ToyMaker]

I got to wondering about this so I dug through some of my reference books and came up with this. Hope it will help those who, like me, are building.

Single strand copper wire at room temperature (about 75 degrees F).

AWG	Amps
10      30
12	20
14	15
16	10
18	5
20	3.3
22	2.1
24	1.3
26	0.8
28	0.5

The above are approximate values (ymmv).
Stranded wire has a higher current rating for a given gage size. The conversion from stranded-to-solid is about:

No. of		Derating
strands		Factor
 2-5		0.8
 6-15		0.7
 16-30		0.5

This means that 20-strand 22 gage wire could carry over 4 amps safely .

robotic regards,

Tom

[anoel]

I have to chime in here...

By far the best wire supplier that I've found has been

http://www.apexjr.com

I buy all of my Teflon jacketed wire from them. Teflon jacketed wire does'nt melt under the soldering iron (at all). Has a smaller diameter due to the thinner jacket and has a higher over all max temp rating. And his prices are much better than the rest of the telfon wire suppliers out there that I've found.

His single conductor shielded wire is great too... for those of you that ever need signal shielding.

[Zephrant]

Was your table for AC or DC current?

Note that the table are designed for an "acceptable" heating of the wire, in a closed conduit with other similar wires also being heated via current.

You could be ok via the Amp rating, but be dropping several volts across the wire under load. Your 24V supply would only be delivering 20V or less at the motor 10 feet away, if you use too small of wire.

HTH-


Zeph

[ToyMaker]

The table data are for single wires in free air carrying dc, I think. I'll have to check the book I found it in. And IR drop in the wiring is why you try keep the lines as short as possible between the driver and the motor .

robotic regards,

Tom

[Zephrant]

Sounds like you have all the right information then. I have yet to master the art of "Just enough" so I tend to go one size larger. I can't stand to see a motor on less than 16 AWG though.


Zeph